The invention relates to a device for connecting components made of fusible plastic, particularly pipes of a fuel line, or for connecting a fuel line with a fuel tank of a vehicle.
European patent application no. EP 919,761 discloses a device of this type which comprises a sleeve body for connecting two pipe ends. In the inside surface of the substantially hollow cylindrical sleeve body a heating element is arranged, which is configured as a heating coil made of resistance wire and to which a current or electric energy can be applied. The wire ends of the heating element configured as a heating coil extend to the exterior into sockets. With corresponding contacts of connecting lines, the electrical connection with a welding device can be established to supply the heating element with current and thereby to heat the plastic so that an electric weld is produced.
Such electric welding sleeves have been used very successfully to connect pipes in supply networks, e.g., water pipes or gas pipes. However, the personnel must be experienced in handling the welding device and producing the electric weld, and the welding operation has to be carefully prepared and executed. Also, the production of such welding sleeves, particularly with respect to the contacting of the wire ends in said sockets is quite complex. To prepare and execute the electric welding operation, various actions must be performed manually, which involves a considerable amount of time and assembly.
Especially in automotive fuel tank systems with a plastic fuel tank and a plastic fuel line that is to be connected therewith, the current joining techniques consist of using hose connecting clamps or butt-welding of the connecting points with heat reflectors. The drawback is that there is no adequate diffusion barrier and complex assembly is required during production, especially since a variety of different components are required. Also, any repair or replacement of individual components requires a substantial amount of time.
In addition, there is the problem of positioning add-on devices, e.g., fuel pump, hose holder, sensors, etc. in and on the tank. The currently used butt-welding process with heat reflectors is difficult, especially in the interior of the tank and/or on surfaces that are not flat. It should moreover be noted that for diffusion reasons, all additional openings on the fuel tank should be avoided, so that the positioning of additional devices in areas of the tank that are remote and/or difficult to access requires a significant amount of time and is often not possible without an auxiliary opening.
When add-on devices or other parts are butt-welded with heat reflectors in the interior of the tank, a heat reflector is brought to the welding position through the existing tank opening, i.e., the opening for the tank fitting, by means of a complex telescope mechanism in order to melt the tank wall at that point. Since the additional device cannot be carried along directly for lack of space, the heat reflector must first be withdrawn and the additional device must then be brought to the desired position. Since a properly welded joint requires a predefined welding temperature and contact pressure, process control is very difficult and costly.